Règle correspondante
Switzerland
Practice Relating to Rule 145. Reprisals
Switzerland’s Basic Military Manual (1987) states: “Reprisals are measures contrary to international law taken by one of the belligerents to punish unlawful acts committed by the enemy Power and to bring them to a halt.” 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 197(1).
Switzerland’s Aide-Memoire on the Ten Basic Rules of the Law of Armed Conflict (2005) states: “All forms of retaliation are prohibited.” 
Switzerland, The Ten Basic Rules of the Law of Armed Conflict, Aide-memoire 51.007/IIIe, Swiss Army, issued based on Article 10 of the Ordinance for Organization of the Federal Department for Defence, Civil Protection and Sports dated 7 March 2003, entry into force on 1 July 2005, Rule 3.
Switzerland’s Regulation on Legal Bases for Conduct during an Engagement (2005) states: “Indiscriminate attacks, i.e. attacks which cannot distinguish between protected persons/objects and military objectives, as well as attacks directed against protected persons/objects or acts of revenge are prohibited in any place and at any time.” 
Switzerland, Bases légales du comportement à l’engagement (BCE), Règlement 51.007/IVf, Swiss Army, issued based on Article 10 of the Ordinance on the Organization of the Federal Department for Defence, Civil Protection and Sports of 7 March 2003, entry into force on 1 July 2005, § 225.
(emphasis in original)
During discussions on reprisals in Committee I of the CDDH, Switzerland stated that it supported the French amendment on a prohibition of reprisals “in principle”. 
Switzerland, Statement at the CDDH, Official Records, Vol. IX, CDDH/I/SR.46, 28 April 1976, p. 65, § 50.
In 1988, in a note on the prohibition on the use of chemical weapons, the Swiss Federal Department of Foreign Affairs stated: “The 1925 [Geneva Gas] Protocol declares a custom.” It added: “The 1925 [Geneva Gas] Protocol and custom prohibit the first use of chemical weapons and accept the lawfulness of second use only in the case of reprisals in kind.” 
Switzerland, Note of the Directorate for Public International Law of the Federal Department of Foreign Affairs, 15 December 1988, reprinted in Annuaire Suisse de Droit International, Vol. 46, 1989, pp. 244–247 (in French) and in Marco Sassóli and Antoine A. Bouvier, How Does Law Protect in War?, ICRC, Geneva, 1999, pp. 608–610 (in English).
Switzerland’s ABC of International Humanitarian Law (2009) states:
Reprisals
International humanitarian law does not include any general prohibition of reprisals. There are however numerous provisions that prohibit specific types of reprisal, in particular reprisals against Protected persons such as Civilians, the wounded and Prisoners of war. Also prohibited are reprisals against certain specific objects such as cultural property and places of worship, the natural environment, and installations that may cause a dangerous situation to occur (e.g. nuclear power stations and dams). 
Switzerland, Federal Department of Foreign Affairs, ABC of International Humanitarian Law, 2009, p. 37.
Switzerland’s Basic Military Manual (1987), in its introductory remarks, states:
In case an adversary should not respect these international rules [“rules of international public law in times of armed conflict”], only the Conseil fédéral [Federal Council] would be competent to decide which measures would be opportune, especially possible reprisals, or to give the necessary instructions to the command of the army. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Introductory remarks, p. III.
In a provision dealing with reprisals, the manual further states: “Only the Conseil fédéral [Federal Council] is competent to order possible reprisals.” 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 197(1).